Thermal expansion and phase transformation in the rare earth di-titanate ( R 2 Ti 2 O 7 ) system
Thermal expansion and phase transformation in the rare earth di-titanate ( R 2 Ti 2 O 7 ) system
复制标题
稀土二钛酸盐(R 2 Ti 2 O 7 )体系的热膨胀和相变
DOI：
10.1107/s2052520621004479
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Kriven, Waltraud M.
中科院分区：
文献类型：
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作者：
Hulbert, Benjamin S.;McCormack, Scott J.;Tseng, Kuo-Pin;Kriven, Waltraud M.
稀土二钛酸盐的热膨胀特性对于它们在高温结构和介电应用中的应用是重要的。采用溶液空间包埋法首次合成了稀土二钛酸盐R2Ti2O7（或R2O3·2TiO2）（R = La，Pr，Nd，Sm，Gd，Dy，Er，Yb，Y）的粉末样品，其晶型为单斜或立方相。这些多晶粉末样品的三维热膨胀是通过在空气中从25 ° C到1600 ° C的原位同步粉末衍射测量的，比其他原位热膨胀研究高出近600 ° C。同步辐射实验中的高温是用四极灯炉实现的。中子粉末衍射测量从25 ° C至1150 ° C的单斜相。La2Ti2O7的稀土二钛酸盐成员在加热时经历单斜晶系到正交晶系的位移转变，如在885 ° C（864 ° C-904 ° C）的空气中的同步辐射衍射和在874 ° C（841 ° C-894 ° C）的中子衍射所示。
Characterization of the thermal expansion in the rare earth di-titanates is important for their use in high-temperature structural and dielectric applications. Powder samples of the rare earth di-titanates R2Ti2O7 (or R2O3·2TiO2), where R = La, Pr, Nd, Sm, Gd, Dy, Er, Yb, Y, which crystallize in either the monoclinic or cubic phases, were synthesized for the first time by the solution-based steric entrapment method. The three-dimensional thermal expansions of these polycrystalline powder samples were measured by in situ synchrotron powder diffraction from 25°C to 1600°C in air, nearly 600°C higher than other in situ thermal expansion studies. The high temperatures in synchrotron experiments were achieved with a quadrupole lamp furnace. Neutron powder diffraction measured the monoclinic phases from 25°C to 1150°C. The La2Ti2O7 member of the rare earth di-titanates undergoes a monoclinic to orthorhombic displacive transition on heating, as shown by synchrotron diffraction in air at 885°C (864°C–904°C) and neutron diffraction at 874°C (841°C–894°C).